Type A personality is a term used to describe people who display the following behaviors:

Insatiable desire to achieve their goals

Strong willingness to compete in all situations

Strong desire for recognition and advancement

Desire to multitask under time constraints

Always in a rush to finish activities

Above average mental and physical alertness

It was first described as an important risk factor in coronary disease in the 1950s by cardiologists Meyer Friedman, R. H. Rosenham, and their co-workers. Friedman & Rosenham estimated that Type A behavior doubles the risk of coronary heart disease in otherwise healthy men and women. The long-range effect of this finding was the development of the field of health psychology, in which psychologists look at how a person's mental state affects his or her physical state.

In some cases, as first demonstrated by Dr. Redford Williams, a cardiologist at Duke University, Type A behavior may not to be a risk factor for coronary heart disease. According to Williams, the lethal part of Type A personality (the expression of hostility and anger) is the only significant risk-factor. Williams named the tendency to hostility and anger the Type H personality.

Furthermore, a systematic review of clinical evidence by Bunker et al recently concluded that there is no evidence for a causal association between Type A behaviour and coronary heart disease.

The most common instrument for diagnosing Type A personality is the Jenkins activity survey, first published in 1979 and based on research going back to the 1940's.